A touch sensing system includes a pen including at least one resonant circuit embedded therein, XY electrodes including X electrodes and Y electrodes perpendicular to the X electrodes, an antenna surrounding the XY electrodes, and a first touch driving circuit which supplies a resonant inductive signal to the XY electrodes, decides a location of the pen based on a resonance magnitude of a resonance signal received through the antenna, and decides a pen pressure of the pen based on a resonant frequency of the resonant circuit and an adjacent frequency of the resonant frequency measured while varying a frequency of the resonant inductive signal.
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1. A touch sensing system comprising: a pen including at least one resonant circuit embedded therein; a touch panel including X electrodes and Y electrodes perpendicular to the X electrodes; an antenna that surrounds the X and the Y electrodes; and a first touch driving circuit configured to supply a resonant inductive signal to the X and the Y electrodes, decide a location of the pen with respect to the touch panel based on a resonance magnitude of a resonance signal received through the antenna, and decide a pen pressure of the pen on the touch panel based on a resonant frequency of the resonant circuit and an adjacent frequency of the resonant frequency measured while varying a frequency of the resonant inductive signal.
A touch sensing system detects pen input and pressure. It uses a pen with an embedded resonant circuit. A touch panel has X and Y electrodes, with an antenna surrounding them. A driving circuit sends a resonant inductive signal to the X and Y electrodes. The system determines the pen's location based on the resonance magnitude received by the antenna. Pen pressure is determined from the resonant frequency of the pen's circuit and how that frequency changes as the driving signal's frequency is adjusted.
2. The touch sensing system of claim 1 , wherein the first touch driving circuit transmits the resonant inductive signal to the pen through electric coupling and allows the resonance signal of the pen to be received by the antenna through an electromagnetic resonance path.
The touch sensing system from the previous description works by sending the resonant inductive signal to the pen via electric coupling. The resonance signal from the pen is then received by the antenna through electromagnetic resonance. This means the pen doesn't need to be directly connected, and the signal travels wirelessly between the electrodes, the pen, and the antenna.
3. The touch sensing system of claim 1 , wherein a resonant frequency fo of the pen and an amount P of the pen pressure of the pen are calculated by the following equations: f 0 = f 1 R 1 + f 2 R 2 + f 3 R 3 R 1 + R 2 + R 3 where f2 is a resonant frequency of the resonance signal having a maximum magnitude, f1 and f3 are adjacent frequencies of the resonant frequency f2, and R1, R2, and R3 are magnitudes of the resonance signal measured at the resonant frequency f2 and the adjacent frequencies f1 and f3, P = f pmin - f pcur f pmin - f pmax × P s where ‘fpmin’ is the resonant frequency when the pen pressure has a minimum value within a pen pressure scale ‘fmax’ is the resonant frequency when the pen pressure has a maximum value within the pen pressure scale and ‘fcur’ is the resonant frequency of the pen pressure to be currently measured and Ps is a predetermined constant.
The touch sensing system from the first description calculates the pen's resonant frequency (f0) and pressure (P) using these equations: f0 = (f1*R1 + f2*R2 + f3*R3) / (R1 + R2 + R3), where f2 is the resonant frequency with maximum magnitude, f1 and f3 are adjacent frequencies, and R1, R2, and R3 are signal magnitudes at those frequencies. Pen pressure P = ((fpmin - fpcur) / (fpmin - fpmax)) * Ps, where fpmin is the minimum resonant frequency, fpmax is the maximum resonant frequency, fpcur is the current measured frequency, and Ps is a constant. This allows for precise pressure sensing based on frequency shifts.
4. The touch sensing system of claim 1 , wherein the resonant circuit includes a first resonant circuit connected to a first tip and a second resonant circuit connected to a second tip, wherein a resonant frequency band of the first resonant circuit is different from a resonant frequency band of the second resonant circuit.
In the touch sensing system from the first description, the pen's resonant circuit contains two separate resonant circuits. A first resonant circuit is connected to a first pen tip, and a second resonant circuit is connected to a second pen tip. Each resonant circuit has a different resonant frequency band, allowing the system to distinguish between input from the two different tips.
5. The touch sensing system of claim 4 , wherein the first touch driving circuit alternately supplies a first resonant inductive signal for driving the first resonant circuit and a second resonant inductive signal for driving the second resonant circuit to the X and the Y electrodes.
In the touch sensing system with two pen tips from the previous description, the driving circuit alternates between sending a first resonant inductive signal for the first resonant circuit and a second resonant inductive signal for the second resonant circuit. This allows the system to individually stimulate and read data from each pen tip separately.
6. The touch sensing system of claim 5 , wherein the first touch driving circuit determines locations of the first and second tips based on the resonance magnitude of the resonance signal received through the antenna, wherein the first touch driving circuit decides a pen pressure of the first tip based on a first resonant frequency output from the first resonant circuit and an adjacent frequency of the first resonant frequency while varying a frequency of the first resonant inductive signal, wherein the first touch driving circuit decides a pen pressure of the second tip based on a second resonant frequency output from the second resonant circuit and an adjacent frequency of the second resonant frequency while varying a frequency of the second resonant inductive signal.
The two-tipped pen touch sensing system from the previous descriptions determines the location of each tip using resonance magnitude received through the antenna. The pressure of the first tip is based on the first resonant frequency and adjacent frequencies as the first inductive signal is varied. Likewise, the pressure of the second tip is based on the second resonant frequency and adjacent frequencies as the second inductive signal is varied. This enables independent location and pressure sensing for each pen tip.
7. The touch sensing system of claim 1 , further comprising a second touch driving circuit configured to supply a stimulus signal to the Y electrodes and receive charges through the X electrodes in synchronization with the stimulus signal.
The touch sensing system from the first description also includes a second touch driving circuit. This second circuit applies a stimulus signal to the Y electrodes and receives charges through the X electrodes, synchronized with the stimulus signal. This likely refers to a capacitive sensing element used in conjunction with the resonant sensing system to improve accuracy.
8. The touch sensing system of claim 1 , further comprising a second touch driving circuit configured to supply a stimulus signal to the X electrodes and the Y electrodes and receive charges through the X electrodes and the Y electrodes in synchronization with the stimulus signal.
The touch sensing system from the first description also includes a second touch driving circuit. This second circuit applies a stimulus signal to both the X and Y electrodes and receives charges through both the X and Y electrodes, synchronized with the stimulus signal. This likely refers to a capacitive sensing element used in conjunction with the resonant sensing system to improve accuracy.
9. The touch sensing system of claim 1 , wherein the antenna comprises a single antenna surrounding the X and the Y electrodes.
The touch sensing system from the first description utilizes a single antenna that surrounds both the X and Y electrodes. This single antenna is used to receive the resonance signals from the pen.
10. The touch sensing system of claim 9 , wherein the first touch driving circuit includes: an analog signal processing unit configured to amplify an analog resonance signal received through the antenna, extract a frequency band of the resonance signal of the pen, and output a digital resonance signal; a Tx driver configured to generate the resonant inductive signal of the pen and sequentially supply the resonant inductive signal to the X and the Y electrodes; a digital demodulator configured to extract a real part and an imaginary part from the digital resonance signal of the pen and output a result of accumulating each of the real part and the imaginary part n times, where n is a positive integer equal to or greater than 2; and a location and pen pressure decision unit configured to calculate a root mean square (RMS) value of data input from the digital demodulator and decide a magnitude and a resonant frequency of the resonance signal.
In the touch sensing system from the first description, the first driving circuit comprises: an analog signal processing unit that amplifies the received analog signal, extracts the pen's resonant frequency, and outputs a digital resonance signal; a Tx driver that generates and sequentially supplies the resonant inductive signal to X and Y electrodes; a digital demodulator that extracts the real and imaginary parts from the digital signal, and accumulates each part n times; and a location and pen pressure decision unit that calculates the root mean square (RMS) of demodulated data to determine resonance magnitude and frequency.
11. The touch sensing system of claim 10 , wherein the analog signal processing unit includes: an amplifier configured to amplify the analog resonance signal received through the antenna; a band pass filter configured to cut off a frequency band excluding a resonant frequency of the pen from an output of the amplifier; and an analog-to-digital converter configured to convert an output of the band pass filter into the digital resonance signal.
The analog signal processing unit in the touch sensing system from the previous description contains: an amplifier to boost the analog signal from the antenna; a band-pass filter that blocks frequencies outside the pen's resonant frequency range; and an analog-to-digital converter (ADC) that changes the filtered analog signal into a digital signal.
12. The touch sensing system of claim 11 , wherein the digital demodulator includes: a first oscillator configured to output a first oscillating signal, of which a frequency and a phase are the same as the resonance signal of the pen received through the antenna; a first multiplier configured to multiply the first oscillating signal by the resonance signal of the pen received through the antenna and output a multiplication result; a first low pass filter configured to remove a high frequency noise from an output of the first multiplier; a first integrator configured to add data input from the first low pass filter n times and supply an addition result to the location and pen pressure decision unit; a second oscillator configured to output a second oscillating signal, which has the same frequency as the resonance signal of the pen received through the antenna and a phase delayed from the resonance signal by 90°; a second multiplier configured to multiply the second oscillating signal by the resonance signal of the pen received through the antenna and output a multiplication result; a second low pass filter configured to remove a high frequency noise from an output of the second multiplier; and a second integrator configured to add data input from the second low pass filter n times and supply an addition result to the location and pen pressure decision unit.
The digital demodulator of the touch sensing system from the previous descriptions has: a first oscillator that creates a signal with the same frequency and phase as the pen's resonance; a first multiplier that multiplies the oscillator signal by the received resonance signal; a first low-pass filter to remove high-frequency noise; a first integrator that sums the filtered data n times and sends it to the decision unit; a second oscillator with the same frequency but a 90-degree phase shift; a second multiplier; a second low-pass filter; and a second integrator feeding into the decision unit. This quadrature demodulation extracts real and imaginary components.
13. The touch sensing system of claim 1 , wherein the pen operates independent of separate electric power.
A touch sensing system detects touch inputs from a stylus or pen without requiring the pen to have its own power source. The system includes a touch-sensitive surface and a pen with a conductive tip. The pen generates touch signals by capacitively coupling with the touch-sensitive surface when the tip contacts the surface. The system processes these signals to determine the pen's position and movement. The pen operates passively, relying solely on the touch-sensitive surface's sensing circuitry for power and signal detection. This design eliminates the need for batteries or external power in the pen, reducing cost and complexity while ensuring reliable operation. The system may also distinguish between pen inputs and finger touches based on signal characteristics, such as amplitude or frequency. The touch-sensitive surface may use a grid of electrodes to detect changes in capacitance caused by the pen's conductive tip, enabling precise tracking. The system may further include calibration mechanisms to adjust sensitivity and reduce interference from environmental factors. This approach enhances usability by simplifying pen design and ensuring consistent performance.
14. The touch sensing system of claim 13 , wherein the resonant circuit of the pen includes an inductor and a capacitor, wherein the inductor includes a first coil wound on a ferrite core, a second coil wound on a guide core, and a spring positioned between the ferrite core and the guide core, wherein the first and second coils are connected in series to each other.
The pen's resonant circuit from the previous description includes an inductor and a capacitor. The inductor is made of a first coil wound on a ferrite core, a second coil wound on a guide core, and a spring between the two cores. The first and second coils are connected in series. The spring and core assembly likely allows the resonant frequency to change based on applied pressure.
15. A method for driving a touch sensing system including a pen including at least one resonant circuit embedded therein, a touch panel including X electrodes and Y electrodes perpendicular to the X electrodes, and an antenna surrounding the X and the Y electrodes, the method comprising: deciding a location of the pen with respect to the touch panel based on a resonance magnitude of a resonance signal received through the antenna; and deciding a pen pressure of the pen on the touch panel based on a resonant frequency of the resonant circuit and an adjacent frequency of the resonant frequency measured while varying a frequency of a resonant inductive signal.
A method for driving a touch sensing system with a pen (containing a resonant circuit), a touch panel (with X and Y electrodes), and an antenna (surrounding the electrodes) involves: determining the pen's location based on the resonance magnitude received by the antenna; and determining the pen's pressure based on the pen's resonant frequency and changes in frequency as the driving signal's frequency is adjusted.
16. The method of claim 15 , further comprising: transmitting the resonant inductive signal to the pen through electric coupling; and allowing a resonance signal of the pen to be received by the antenna through an electromagnetic resonance path.
The touch sensing method from the previous description transmits the resonant inductive signal to the pen via electric coupling, and the pen's resonance signal is received by the antenna through electromagnetic resonance.
17. The method of claim 15 , wherein a resonant frequency fo of the pen and an amount P of the pen pressure of the pen are calculated by the following equations: f 0 = f 1 R 1 + f 2 R 2 + f 3 R 3 R 1 + R 2 + R 3 where f2 is a resonant frequency of a resonance signal having a maximum magnitude, f1 and f3 are adjacent frequencies of the resonant frequency f2, and R1, R2, and R3 are magnitudes of the resonance signal measured at the resonant frequency f2 and the adjacent frequencies f1 and f3, P = f pmin - f pcur f pmin - f pmax × P s where ‘fpmin’ is the resonant frequency when the pen pressure has a minimum value within a pen pressure scale, ‘fmax’ is the resonant frequency when the pen pressure has a maximum value within the pen pressure scale, ‘fcur’ is the resonant frequency of the pen pressure to be currently measured and Ps is a predetermined constant.
The touch sensing method from the previous description calculates the pen's resonant frequency (f0) and pressure (P) using: f0 = (f1*R1 + f2*R2 + f3*R3) / (R1 + R2 + R3), where f2 is the resonant frequency with maximum magnitude, f1 and f3 are adjacent frequencies, and R1, R2, and R3 are signal magnitudes at those frequencies. Pen pressure P = ((fpmin - fpcur) / (fpmin - fpmax)) * Ps, where fpmin is the minimum resonant frequency, fpmax is the maximum resonant frequency, fpcur is the current measured frequency, and Ps is a constant.
18. A user interface comprising: a display; a touch sensing system comprising: a pen including a resonant circuit embedded therein; a touch panel including X electrodes and Y electrodes perpendicular to the X electrodes; an antenna that surrounds the X and the Y electrodes; and a first touch driving circuit configured to supply a resonant inductive signal to the X and the Y electrodes, decide a location of the pen with respect to the touch panel based on a resonance magnitude of a resonance signal received through the antenna, and decide a pen pressure of the pen on the touch panel based on a resonant frequency of the resonant circuit and an adjacent frequency of the resonant frequency measured while varying a frequency of the resonant inductive signal; a processor and memory configured to analyze a received signal of the antenna to estimate a location and a pen pressure of the pen on the display.
A user interface includes a display, a touch sensing system, a processor, and memory. The touch sensing system consists of a pen with a resonant circuit; a touch panel with X and Y electrodes; an antenna surrounding the electrodes; and a driving circuit that sends a resonant inductive signal to the electrodes. The system determines pen location based on resonance magnitude received by the antenna and pen pressure based on the resonant frequency of the pen's circuit and how that frequency changes when the driving signal's frequency is adjusted. The processor and memory analyze the signal to estimate location and pressure.
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September 25, 2014
March 14, 2017
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